A high-affinity, partial antagonist effect of 3,4-diaminopyridine mediates action potential broadening and enhancement of transmitter release at NMJs.
A high-affinity, partial antagonist effect of 3,4-diaminopyridine mediates action potential broadening and enhancement of transmitter release at NMJs.
复制标题
DOI：
10.1016/j.jbc.2021.100302
复制
发表时间：
2021-01
期刊：
影响因子：
--
通讯作者：
Meriney SD
中科院分区：
文献类型：
--
作者：
Ojala KS;Ginebaugh SP;Wu M;Miller EW;Ortiz G;Covarrubias M;Meriney SD
3，4-二氨基吡啶（3，4-DAP）增加神经肌肉接头（NMJ）的递质释放，低剂量的3，4-DAP（估计血清中达到101 μM）是美国食品药品监督管理局（FDA）批准的治疗Lambert-Eaton肌无力综合征引起的神经肌肉无力的药物。通常认为，3，4-DAP可阻断电压门控钾（Kv）通道，导致突触前动作电位（AP）延长。然而，最近的报道显示，低毫摩尔浓度的3，4-DAP对电压门控钙（Cav）通道的Cav 1亚型（“L型”）具有脱靶激动剂效应，并且推测这种激动剂效应可能有助于3，4-DAP对NMJ处的递质释放的效应。为了阐明3，4-DAP的作用机制，我们首先使用膜片钳电生理学来表征3，4-DAP对在哺乳动物NMJ处发现的主要突触前Kv通道亚型（Kv3.3和Kv3.4）的浓度依赖性阻断。除了众所周知的低亲和力（0.1-1 mM）拮抗剂活性外，我们还发现了3，4-DAP的一种先前未报道的高亲和力（1-10 μM）部分拮抗剂效应。我们还发现1.5 μM DAP对Cav1.2或Cav2.1电流没有影响。接下来，我们使用电压成像显示1.5或100 μM 3，4-DAP以剂量依赖性方式加宽AP波形，与Cav 1钙通道无关。最后，我们证明了1.5或100 μM 3，4-DAP以剂量依赖性方式增加递质释放，这种效应也不依赖于Cav 1通道。从这些结果中，我们得出结论，低微摩尔浓度的3，4-DAP仅作用于Kv通道，以介导AP增宽并增强NMJ处的递质释放。
3,4-Diaminopyridine (3,4-DAP) increases transmitter release from neuromuscular junctions (NMJs), and low doses of 3,4-DAP (estimated to reach ∼1 μM in serum) are the Food and Drug Administration (FDA)-approved treatment for neuromuscular weakness caused by Lambert–Eaton myasthenic syndrome. Canonically, 3,4-DAP is thought to block voltage-gated potassium (Kv) channels, resulting in prolongation of the presynaptic action potential (AP). However, recent reports have shown that low millimolar concentrations of 3,4-DAP have an off-target agonist effect on the Cav1 subtype (“L-type”) of voltage-gated calcium (Cav) channels and have speculated that this agonist effect might contribute to 3,4-DAP effects on transmitter release at the NMJ. To address 3,4-DAP’s mechanism(s) of action, we first used the patch-clamp electrophysiology to characterize the concentration-dependent block of 3,4-DAP on the predominant presynaptic Kv channel subtypes found at the mammalian NMJ (Kv3.3 and Kv3.4). We identified a previously unreported high-affinity (1–10 μM) partial antagonist effect of 3,4-DAP in addition to the well-known low-affinity (0.1–1 mM) antagonist activity. We also showed that 1.5-μM DAP had no effects on Cav1.2 or Cav2.1 current. Next, we used voltage imaging to show that 1.5- or 100-μM 3,4-DAP broadened the AP waveform in a dose-dependent manner, independent of Cav1 calcium channels. Finally, we demonstrated that 1.5- or 100-μM 3,4-DAP augmented transmitter release in a dose-dependent manner and this effect was also independent of Cav1 channels. From these results, we conclude that low micromolar concentrations of 3,4-DAP act solely on Kv channels to mediate AP broadening and enhance transmitter release at the NMJ.
登录
查看更多内容
影响因子：
5.5
作者：
Flink, MT;Atchison, WD
通讯作者：
Atchison, WD
影响因子：
5.3
作者：
Ginebaugh, Scott P.;Cyphers, Eric D.;Meriney, Stephen D.
通讯作者：
Meriney, Stephen D.
影响因子：
5.5
作者：
DODGE, FA;RAHAMIMO.R
通讯作者：
RAHAMIMO.R
影响因子：
2.8
作者：
Banwell, BL;Ohno, K;Engel, AG
通讯作者：
Engel, AG
DOI：
10.1111/j.1749-6632.1999.tb11284.x
发表时间：
1999-01-01
期刊：
MOLECULAR AND FUNCTIONAL DIVERSITY OF ION CHANNELS AND RECEPTORS
影响因子：
--
作者：
Catterall, WA
通讯作者：
Catterall, WA